Always Heat from 2009 MZ5 front Vents. Anyone have this problem?

G

GBean

Ancient Datsun FTW!
:
09 Mazda5T, 71 Datsun 510
SO our 2009 MZ5 is great, save one issue. the air vents in the dash always blow hotter than ambient temp air. Like 10 Degrees hotter.

The AC works ok, and blows cool air, but with the temp all the way down and the AC off, the air is uncomfortably warm.

I read about an issue with engine bay air being sucked in through the passenger intake below the windshield on the Mazda 6, and that some well placed weather stripping fixed it.

Any ideas anyone?
 
I'm so sorry I haven't gotten around to doing a how-to for this. It takes hours to take pictures, caption and describe everything in detail.

I can say though that I had to undo the previous evaporator temperature sensor mod (50k ohm resistor in parallel) because we had the system freezing up repeatedly. If I can get ahead on other chores, I will get the how-to put together.
 
So what is the solution? I could probably figure it out without a how to.
 
GBean said:
So what is the solution? I could probably figure it out without a how to.
Click to expand...

I noticed the same problem when driving along as well. It seemed as though the engine bay heat was coming in through the vents while the vehicle was in motion. I took a shot in the dark and pressed the recirculation button, and it solved the problem. Button off, hot air coming in, button on, no air coming in.
 
qcoffey said:
I noticed the same problem when driving along as well. It seemed as though the engine bay heat was coming in through the vents while the vehicle was in motion. I took a shot in the dark and pressed the recirculation button, and it solved the problem. Button off, hot air coming in, button on, no air coming in.
Click to expand...

There's more to the problem on these cars then just the recirculate function letting in hot air. Hot or cold outside, if the A/C is off, my feet are always burning up and I can feel the heat coming through cracks in the trim down below the dash. Doesn't matter whether it's on fresh or recirculate. I don't drive the car anymore and my fiancee doesn't seem to care because she's always cold. Maybe it's a built-in wussy comfort function. J/K
 
Mine always blows cold air at the feet if the temp is turned down.
I believe that is because the A/C compressor is automatically turned on when either on floor or defrost to de-humidify the air.
 
Also I think I should add that mine has the AUTO climate control, not just a temp select knob.
 
FYI - '08+ has automatic climate control as standard.

You should be aware that 72* AUTO setting does not output the same air temperature as 72* with manual control. You may find that the warmth subsides if you set the temp to 60* before turning OFF the system.
 
My car blows hotter than ambient air regardless of what the temp was set to when shut off.
Also, who has air blowing with the system off?

What I am saying is that with the system on, and set to 60* with the AC off, if it is 70* outside, it blows roughly 78-80* air through the upper vents.
 
If you have the a/c OFF, the temperature at 60*, and recirculate OFF, it will be warmer that just opening the windows. This has been the case for every vehicle I can remember as all of them pulled fresh air from the firewall area.

I have had to remove the windshield cowl because of a rodent (did a 'How-To' as well) a couple years back, and I would say that there is not much you can do to insulate or weatherstrip that area. There is a pretty large volume of space below the wipers that the fresh air intakes from and some water drain holes that lead to the top rear of the engine bay firewall. You will always get engine heat. If you are simply seeking fresh air though, I have found it best to set it to windshield and crack the moon roof.
 
flcruising said:
I have found it best to set it to windshield and crack the moon roof.
Click to expand...

That's good info... just a note though, that setting it to windshield will run the compressor/AC... which of course will send you cool air, but which defeats the purpose of what he's asking.
 
Sorry again, since I can't say that I run the blower without the need for either heat or a/c, I keep referring to it through my use of the system being OFF, which means recirculate turns OFF by default.
 
Yes we understand what you are saying. A/C off, blower off and recirculate mode off. Just open ambient air running through the vents. Every vehicle has always warmed up the ambient air passing through partly due to the air intake being close to the firewall which is hot and the fact that the air ducts naturally get hot inside the dash that is constantly sitting under direct sunlight whether parked or driving. If it bothers you so much turn on the recirculate on and roll down the windows or open up your moonroof if you have one. It's not a big deal.
 
Recirc. on doesn't change it. With the fan off I don't notice. With the fan on it is ridiculous. The Mazda 6 had a similar problem that was fixed with weather stripping. I see a spot where air from the engine bay is probably leaking around the sides of the intake cowl and will try to seal it up and check if it improves anything.
And yes, my 09 GT hs a moon roof.
 
never noticed this issue and I've had my '09 since new. if I'm not using A/C (though I pretty much do from april to oct!) I haven't felt 'warm' air through the vents. I just set the temp to 60 and manually turn down the fan.
 
GBean said:
Recirc. on doesn't change it. With the fan off I don't notice. With the fan on it is ridiculous. The Mazda 6 had a similar problem that was fixed with weather stripping. I see a spot where air from the engine bay is probably leaking around the sides of the intake cowl and will try to seal it up and check if it improves anything.
And yes, my 09 GT hs a moon roof.
Click to expand...
I think you and I are the only two that have this issue or others simply don't care b/c they leave it on 'auto'.

Can someone who does NOT have this hot recirc air problem do us a big favor. Open your hood and take a picture of the underside (’10 owners perhaps who owned the car since NEW). I wonder if I am missing a seal somewhere from the PO. I still have doubts about inlet air since my glove box gets ridiculously hot (no air flow there but is next to heater core) and problem seem s to subside a little (still hot) if I turn fan off and just let outside air in (recirc off). The fan function is useless b/c it manipulates or magnifies the hot air.
 
I have the same problem... and of all the 10 cars I've owned in the past, never have I had a vehicle that blows air so much warmer than the ambient air. Sorry, I have no solution, but I share your pain. And to contradict what others have said, I don't think it's that difficult to have system that pulls in ambient temp air. All of my previous cars have been able to do this without a problem. Of course at first the air may be a bit warmer because you've been sitting in the sun... but after 10 minutes of driving any normal system will easily clear that air and should be pulling fully ambient temp air.
 
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